It is known to utilize low head systems for hydroelectric generation. However, generation apparatus utilizing the low-head within rivers having flood control dams and spillways has not found widespread usage for a number of reasons. Low-head generating systems may utilize the flow of the current for motive purposes, and such devices are shown in U.S. Pat. Nos. 3,978,345; 4,142,823; 4,163,904 and 4,301,377. It is also known to utilize hydroelectric generating systems of the syphon type in low-head installations, and a sample of such apparatus is shown in U.S. Pat. No. 4,117,676.
A number of dam installations exist in major rivers for flood control purposes, and such dams include a plurality of gated spillways for controlling the water level. Low-head hydroelectric generating apparatus mounted within such spillways would effectively utilize the water flowing therethrough for electric generation purposes, however, during the river flood stages which annually occur such hydroelectric generating apparatus would interfere with the flow of water through the spillways, functioning as a gate, and seriously affect the flood control purpose of the dam. For this reason, hydroelectric generating apparatus has not previously been utilized with low-head dams and spillways of the flood control type in view of the problems arising during high water.
It is an object of the invention to provide a hydroelectric generating system which may be utilized in rivers susceptible to flooding conditions wherein the generating apparatus in no way interferes with flood waters or the operation of the dam for flood control purposes.
Another object of the invention is to provide hydroelectric generating apparatus for use with dams and spillways located within rivers which periodically flood wherein the generating apparatus is only located at its operating position during nonflooding conditions.
Yet another object of the invention is to provide hydroelectric generating apparatus for use with dam spillways in floodable rivers wherein the apparatus may be selectively associated with, and removed from, the spillways depending upon the water level conditions up the river.
A further object of the invention is to provide a hydroelectric generating system for use with river spillways wherein anchor means defined upon the lower regions of the spillway cooperate with a submergible vessel upon which generating apparatus is mounted, the vessel including abutments matingly cooperating with the anchor means.
The method of the invention is practiced by the utilization of a vessel which includes ballast and trim tanks and pumps and valves for controlling the amount of water within such tanks wherein the vessel may be selectively floated or submerged. The vessel includes a plurality of parallel gated passages through which water may flow, and each passage includes a turbine drivingly connected to electric generation means. The lower region of each vessel includes abutment surfaces transversely disposed to the length of the water flow passages for cooperation with anchor means defined upon the lower regions of the river spillways.
Vessels in accord with the invention concepts are floated upstream by means of tugboats or the like into close proximity to dam spillways located within a river. The barge is constructed of a width substantially corresponding to the spillway width, and upon the vessel being properly located to the spillway the ballast and trim tanks are flooded by introducing water from upstream of the dam by gravity flow or by pumps, causing the vessel to submerge to its operating depth within the spillway opening. The spillway gate may then be raised completely from the water, and in effect, the vessel will function as a gate. The water flowing through the spillway enters the vessel passages and drives the associated turbines for electric generation purposes.
Anchor projections formed at the lower region of the spillway cooperate with the abutment surfaces defined upon the vessel wherein the submerged vessel is prevented from being displaced downstream by the spillway anchors, and displacement of the vessel from the spillway opening is only possible after the vessel has been raised from its submerged condition.
The vessel will be located within the spillway opening for the majority of the year. However, when river flooding conditions are expected the vessel pumps and valves are operated to purge the ballast and trim tanks to float the vessel and clear the vessel abutments from the spillway anchors. By means of tugs, or other surface boats, or cable winches, the floating vessel is transported to a safe location during flooding, and water may flow through the spillway unrestricted and controlled by the gate. After the flooding conditions have passed the vessel is retransported to its position adjacent the spillway, its tanks are flooded, and the vessel is submerged to its operative position and placed into operation.
The vessel includes seals along its sides to most effectively utilize the water passing through the spillway, and valves within the vessel passages control the flow of water therethrough.